Method and apparatus for heating



July 15., 1952 F50 HEss 2,603,470

METHOD AND APPARATUS FOR HEATING FEGE y 3N w f INVENTOR.

n FREDEmc o. Hass ATTORNEY.

July 15, 1952 F, 0, HESS 2,603,470

METl-iOD AND APPARATUS FOR HEATING Filed April 26, 1949 3 Sheets-Sheet 2INVENTOR. FREDERIC O. HESS .AT TOR N'EY. l

July 15, 1952 F, o, H555 2,603,470 V METHOD AND APPARATUS FOB HEATINGFiled April 26, 1949 5 Sheets-Sheet 5 O 0*1 mi INVENTOR. FREDERIC O.HESS

` ATTORNEY.

required for rolling.

Patent-ed July 15, 1952 METHOD AND APPARATUS FOR HEATING Frederic O.Hess, Germantown, Pa., assignor to Selas Corporation of America,Philadelphia, Pa., a corporation of Pennsylvania Application April 26,1949, Serial No. 89,606

3 Claims.

The present invention relates to the heating of metal, and moreparticularly to the method of and apparatus for heating slabs or otherlarge bodies'of metal'from ambient lto hot working temperatures such asthe elevated temperatures In accordance with the present invention thereis provided a furnace system including a plurality of aligned furnaceunits through which the slab or other metal piece is moved. The furnaceunits are each provided with a high temperature heating chamber and apreheating chamber that are in direct communication with each other. Thefurnace units on the charge end of the systemv have their preheatingchambers open at the top through which charging takes place, while thosein the main heating portion of the system have their preheating chambersclosed. Conveying means is provided between each of the furnace units tovmove the work through the system with the work in the preheatingchambers moving in one direction and the work in the heating chambersmoving in the opposite direction.` At the end of the system opposite thecharging and discharging end there is provided a transfer mechanism toshift the work vfrom the upper preheating level to the lower heatinglevel.

It is an object of the present invention to provide apparatus forAheating rapidly and evenly slabs, billets, blooms" and other shapes ofmetal. The apparatus isl so designed that the work 'is heated evenlythroughout its area from end to end. With the arrangement of the furnaceunits in the present invention a large portion of the heat normally lostis utilized to raise the temperature of the work to a relatively highvalue prior to the time the work passes into the actual heatingchamber.-

Y It is a further object of the inventionv to provide' apparatus forpreheating work in which the Ahot products of combustion from theheating chamber pass directly tothe preheating chamber lwhile still atsubstantially their highest tempera- 'of the present invention work ismoved by mechanical means, which may be automatic in operation, directlyfrorn the point of loading through the furnace system to the. mill, andis supplied to the mill at mill speed.

It is a further object of the invention to provide a method of heatingmetallic objects which comprises passing themxin opposite directions andat different levels through preheating and heating chambers of a furnacesystem.

In the following description of the invention the work being heated willbe referred to as slabs. It will be understood, however, that the workbeing heated could be billets or blooms or any large pieces or shapes asdesired. o

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, its advantages and specific objects attained with itsv use,reference should be had to the accompanying drawings and descriptivematter in which I have illustrated and described a preferred embodimentof the invention. Y

In the drawings: Y

Figure l is amore or less diagrammatic view showing the furnace lineandthe apparatus used to transfer the billets from one level to another;

Figure 2 is a section of one of the furnace units onv theloading end ofthe system;

Figure 3 is a section of one of theffurnace units in the main heatingportion of the system;

Figure 4 is a section of the transfer mechanism;

Figure 5 is a section of an alternative form in which the furnace unitsmay be supplied; and

Figures 6 to 8 inclusive are diagrams showing the manner in which thesystem operates.

Referring to Figure 1 there is shown more or less diagrammatically theentire heating system to be used for heating slabs, billets, or otherlarge bodies. In this system the furnace includesa plurality of furnaceunits forming the loading zone, which units are indicated at A. Thereare 3 Y alsoY a plurality of furnace units B forming the main heatingsection of the system, and a transfer section C which is used totransfer the pref heated billets to the high temperature heatingchambers of the furnace units.

The furnace units of the loading section are identical as are thefurnace units of the main heating section.V The furnace units of thesesections differ from each other only in that the units ofthe loadingsection are provided with means for'loading the billets to be heatedfrom above, while the units of the `main heating section do not havethis provision.

In Figure 2 there is shown a furnace .unit A which is provided with alower high temperature heating chamber 3 and an upper preheating chamber4 that are directly connected by a passage 5' extending between the twochambers. Each end of the furnace unit is provided-with openings 6through which the slab to be heated may be passed into and out ofchamber 3. Openvings 1 are also providedin the preheating cham- .ber 4through'which the slabs may be passed. It will be Vnoted that Yeach ofthese openings is `considerably smallerthan the size of the chamber andVis only slightlylarger than the dimensionsV of the maximum size slabthat is to be heated. -V f y The walls of the, 'chamber' 3 have in 'themburner blocks 8 which are properly located for the heating patterndesired and which are separated by suitable high temperature refractoryblocks 9. The entire furnace unit is builtY up of the refractory and the.burner blocksand is vsupported by sheet metal backing Il in accordancewith ordinaryjfurnace practice. The furnaces are providedV with bracesl2 and rest upon a platform I3. Y'There are also provided supports YIiiVwhich extend throughout the length of the system and upon which each ofthe furnace units is mounted so that they may be positioned with theopenings and 1 in axial alignment.V The beams M are mounted upon a'suit-Yable floor or 'foundation 15.

Each of the burners` 8 that is used may be of any'desired type that hassuitable combustion characteristics for the size of furnace chamber 6being used. The burnerY disclosed herein are similar to those-describedand claimed in Hess vPatent No. 2,215,079, .issued September 17, 1940.Each of these burners consists of the refractory block 8 that-has a cupIS formedin its face.

lFuel, whichV consists of a combustibleV mixture Aof gas and airis-suppliedthrougha distributor l'! into the c-up in a plurality ofsmall jets where it is completely burned in the cup. The fuel in burnersof this type is burned in the cup to heat Vthe latter to incandescencethereby supplying radiant -heatto thework.V` Heatis also supplied byVthe .hot gases of combustion as will be explained more fully below. Thedistributors I6 are connected-by Apipes i 8 with suitable manifolds andeach pipe |-8 has -a valve I9 in it so that the amount of fuel suppliedto each burner can be regulated individually. Y y

Between'each of the furnace units in both the loadingrr section as wellas the main heating section there .is provided conveying mechanism tomove the VVslabs that are to be heated through the system.l .Asshown inthe drawings there is an upper conveyor roller -2l located between`rolls.

4 There is also provided alower conveyor roll 23 mounted on a shaft 24between each of the furnace units at a level so that slabs can be movedthrough the high temperature furnace chambers. The lower conveyorrollers are so positioned that they will forward slabs to be heatedthrough the high temperature chambers 3. It is notedV that in actual,practice these conveyor rolls and their supportingshafts lwill be watercooled in order to prevent overheating of the Since, however, provisionfor water cooling rolls of this type is Well known, it is deemedunnecessary to describe such provisions in detail herein. The conveyorrolls are driven positively tomove the slabs being heated in the twofurnace' chambers in opposite directions. To this end there is provideda gear 25 on shaft 22 and a gear 2t on shaft 2d. These gears areconnected for rotation together by a pair of idler gears 2l and arepositively driven by a pinion V28d-.on the shaft of a motorx29. While itwould be possible todrive fthe-,various conveyor rollsV from a singlemotor and drive shaftit rhas'V been found preferableto drive each set ofconveyor rolls individually :by its own motor and hook these motorstogether electrically so that they will rotate inunison. It is Y"notedthat at the exit end of the. high temperature heating chambers, asshownat ythe .right `of Figure 1 of the drawing/thereis a pair-of pinchrollers 3| which areused to feedY positivelyV the vheated slabs intosome mechanism for Voperating `upon them such as, forvexample, a.rolling mill.Y

As noted above the 4'furnace units in the main heating section aresimilar to those in the loading section, with the exception thattheupper preheating chainberll in wthese units is closed so that a higherVdegree of preheating maybe obtained. Such larfurnace is shown'in sectionin Figure 3 of the` drawings. The'high temperature heating chamber-ofthe furnace shown in Figure v3 is circular in shape rather thanpolygonal in shapeas'wasV the furnace disclosed in Figure 2. Thisis-amatter of design however, since the shape-the furnace chamber willtake will be determined Yby the size and type of work being heated. InFigure 2 the lower high temperature chamber is shown at 32 andy integralpart ofthe furnace unit and is built each of the furnace units and on alevel so that y slabs can be moved through the preheating chambers. Thisroller is supported on a shaft 22 that is journalled'in any suitablemanner.

,lindrical Vfur-nace chamber.

of vrefractory materials .as is the rest of the furnace unitnln thiscase the furnace units B are mounted on a-pair of Supports 31, the upperpart of which is-semi-circular in shape to support the furnace andthelower part of which is flat to be received on platform I 3.- As notedv above, the burners used in this chamberare exactly the same as thoseused in the heating` chamber described iii-connection with Figure 2. Theonly difference in these burners'is that their outer; contour has to bechanged to fit the cy.-

The conveyors are placed between each of these furnace units as theywere between each of thev units in the loading zone and the conveyorsare driven in the sam-e manner.

In the operationV of the system, asvwill be pointed out more indetailbelow, slabs are loaded into the preheating chamber Vand are moved tothe left in Figure .1. After passing through all -of the furnace unitsthey are moved vertically downward in alignment with` theopenings inthehigh temperature chambers and are then moved to the right to the exit ofthe system. A transl fer mechanism C is used for I lowering/the slabsfrom the preheating to the jhigh temperature chambers.` This transfermechanism includes a trans'ferduct 38 that is, in effect, a tunnelclosedat its left end andl open at itsfrightend so that the'slabs may beinserted and removed'therefrom.'

not driven since the slab is moved into and out of the transfer duct bya pair of pinch rollers 46 and 41 that are mounted on shafts 48 and 49respectively. These shafts are journalled for rotation in bearings 50which are attached to the bracing 42 for the duct and may be driven inopposite directions by means of gearing I from a suitable electric motor52 that is mounted on platform 43.

In order to raise and lower the transfer duct a plurality of plates 53are attached suitably to the beams `44 at various points along thelength of the duct. These plates have pivoted to them a pair of levers54 and 55, the other ends o f which are pivoted'to a rigid support 56.Thus by rotating the levers the entire duct can be moved vertically. Theraising and lowering movement of the duct is accomplished by a lever 51thatis attached for movement withV lever 55 to form a bell crank. Thelower end of the lever 51 is connected by a link 58 to a piston rod 59that has on its'end a piston received in a cylinder 6|. Fluid underpressure can be admitted in any suitable manner main `66 would extendfrom one end of the furnace system to the other tol supply fuel to allof vthe units of which it is comprised. n'

. In order to fire the furnace a combustible mixture of gas and air issupplied through the main 66 and suitablemanifolds to the variousburners of theindividual `furnace units where it is dis- 'chargedina'plurality of small jets to lbe completely burned' in the-cups 16,; ofthe burners. ,The cupsare heated to a lhigh-degree of incan- Adescenceand radiate theirheat to allportions of the furnace chamber whichisalsowheated to incandesence. In effect, the high4 temperature chambers3, 32 and 62 are radiant tunnels through which the slabs are moved sothat they may be evenly heated aroundvtheir entire surface. The hotproducts of combustion which are vproduced as a result of thecombustion,` and which would normally be wasted, risev throughpassages'between the high temperature chambers and the 'preheaterchambers where they circulate around a second slab to preheatl the same.Some of these gases also ow through the openings 6 and 1 to protect theslabsl from;` the atmosphere as theyv are. moved from vone furnaceunitjto the other.

. Thus the slabs are'heated in a series of steps as theypass from o neof the; furnace'units to the other and they are protected'from oxidationas theylmovevbetwee'n the furnace units by means .to opposite ends ofthe cylinder lin order to lower and raise the transfer duct to moveslabs from the upper preheating chambers to a position in which they canbe fed to the lower. high temperal ture chambers.

Each of the furnace units that were described above shows the slabs tobe heated mounted on their sides.- The furnace units, however, could beconstructed so that the slabs are mounted on edge rather than on theirsides if it is so desired. The controlling factor in this case would bethe type of working apparatus to which the slabs are supplied. There isshown in Figure 5 a furnace unit in which the slabs are mounted on edgeas they are being moved through the system. It will be seen that hightemperature chamber'62 and preheating chamber 63 in this case arerectangular in shape with their narrow sides at the top and bottomthereof. These chambers are connected by a passage 64. The furnace unitis constructed, as were the previously described units, in accordancewith ordinary furnace practice and similar parts are given similarreference numerals. The burners used in this type of furnace are alsosimilar to those described above. It is noted. however, that theplacement of the burners is slightly different in that the burners arelocated in the vertical sides of the high temperature chamber and aredirected toward the slab which would be passing between them. In thiscase, each of the pipes that supply the burners is shown as beingconnected to a manifold 65, and the manifolds in turn connected to amain 66. In a system of the type described the of a blanket of exhaustgaseswhich blows through thel entrance and exit openings of each unit.

j A description of the operation'of vthe system will now be made withparticular reference to Figures 6, 7 and 8. It is intendedthat the slabswill by supplied to the system at ambient temperature and dischargedinto larolling mill for hot rolling, -for example,v at a temperature ofabout 2250 F. Inorder toattain this temperature the lower chambers ofthe furnace units are fired at a rate sufficient to maintain the burnercups I6 at substantially 2700 F., and the interior of the chambers Vatthe slightly lower temperature of from ,2 400" Atol 2500o F. The timethe slabs mustbe kept in the furnace units will vary with their analysisand their dimensions, with smaller slabs vrequiring less time to heatthan thosethat are larger. 'I he number of furnace units A and B thatare used will vary with the length of the slabs being heated. As shownherein each slab is of such a length that five furnace units A arerequired'to receive it, and there are provided ten furnace units B. Asmaller or larger numberof units B could be used, but there should bethe samefnumber as there are units A or a multiple thereof. Enoughfurnace units'are disclosed herein to handle six slabs at once. Y I f InFigure 6 slabs D and E are shown in the lower chambers and slab F isshown in the transfer section C,l which is in its lower position, readyto be fed to the lower-heating chambers. Slabs G and H are shown in the"upperA preheating chamber of furnace units'B and a slab I is about to beplaced in the preheating chambers of furnace units A. This may beaccomplished by any suitable'slab handling mechanism, such as anoverhead crane. During this time the conveying mechanism is'beingoperated to move slabs D, E,

Gand H back and forth for a distance at least n .duc to' the exhaustgases encircling the slabs .at .these points, the gases-are notas hot astheinte'ror of the heating .chambers'of the furnace units.r Pinch rollsi6 and di are operated to feed slab F into the.heatingqchambersbelowslab G whileslab I is being placed imposition in thepreheatingrchambers of furnace units A.'

While all six -slabs are in their respective chambers: ofthe, furnaceunits `las shown inA Figure 7; f

sirable to move the slabs .back and forth to insure veven Vheatingthroughout their` length. When slab D is upto temperature it .will bemoved to the left far .enough to be received by pinch rolls 3|. Thepinchrolls will feed the slab rto a rolling millor other mechanism to.perform'work upon-them. ,Thesamef operation .of theconveyingrolls-which `moves slab Dto pinch rolls 3l will 'move .slab .Cfintolpinch r-olls 46, 41 in thev transfer .mechanism'Q YThese latter.rolls will then move the .slab .G .into the transfer duct, as

Y shown in Figure .8 by the'time slab F leaves the heating chamber .ofthe furnace unit A on vthe right end of theline..

The transfer mechanism c win then be moved to its lower position ofFigure 6 carrying the slab F with it. VThe parts are thenin position tostart the heating cycle on a new slab that is to be placedin furnaceunits A, y

With the arrangement shown .the slabs will be Y i8 Y value. Onesuggestcdsystem is a soecalled interlock system in which the fuel supplyis controlled inresponse to the work `temperature and the furnacetemperature is used .as a high limit control. The details of -such acontrol system form Yno part of the present invention so-for that reasonhaveA not .been illustrated, One form that the con-trol systemmay takeis disclosed in Hess et z al. vappli-cation Serial NumberV 761,602,filedJu'ly k from one Vlevel to the other, however, it is 4de- Y heatedto approximately 30.0" F. by the time they` Y .leave'the preheatingchambers to pass into the transfer duct. YDuring their passage through`the lower heating chambers the slabs areraised to a temperature -of2250'L7 F. for hot working. In order to obtain these temperatures acombustible mixture of gas Iand airis burned the cups I8 of the'burners`to heat them to a temperature of 2700" F. The radiation from the cupsassisted by .the hot products of vcombustion will heat the entirev lowerchamber of each furnace unit to a temperature in the neighborhood of2400 F. to 2.500" F. Therefore each chamber comprises a radiant wallentirely .surrounding that portion of the slab received thereby to heattherentire Yarea of the slab evenly. This heating is, of course,assisted by the high temperature products of combustion that are movingthrough the hightem- .perature .chamberrto the preheating chamber.-

The lproducts of combusti-on exhaust through the entrance and exitopenings of each chamber and form a Vblanket of protective gases throughwhich the slabs move from one of the furnace units to the next. Theslabs are therefore protected from oxidation during the time they arebeing heated. As has `been noted-above, the time required for heatingtheslabs lwill varywiththeir dimensions and physical characteristics aswell as the final temperature that is desired. ,In any event, the timerequired will be `a matter of minutes rather than the hour-s that arerequired for heating slabs in the lconventional typeof furnaces. Anysuitable control system may be used to insure that the temperature ofthe Work will be at the desired '17, 1947.y -y f .Y

.Inthe operation of the system slabs. are moved in what is. in effect,4a Acontinuous line through the furnace units. During their travel theyare raised one after another from ambient temperature to the temperaturerequired for hot working, land aredelivered directly .to the hot workingmechanism before they have a chance to cool or become covered with anobjectionable scale.- The arrangement is such that a minimum of space isrequired for the equipment. After theslabs are placed in the.preheatingchambers no further manual handling of them is required.

From the .above `description it will be seen. that I have providedapparatus bymeans of which slabs, billets .or other large pieces vofmetal may be rapidly .heated 'one after another to a desired elevatedtemperature. The invention also Y,dis-

closes a novel method of heating and handling l large pieces o f metal.Y

While in accordance with the provisions of the statutes I haveillustratedand described the best Y form of embodiment 4of my inventionnowiin-ovvn to me ,it will be apparent to those 'skilledV in the artthat changes may be made inthe form ofthe apparatus disclosed Withoutdepartingfrom the spirit Vand scope Yof the invention, as set forth'inthe appended claims, and thatinfsome cases-certainfeatures of myinvention :may be used toadvantage without a corresponding vuse of otherfeatures.

What is claimed is: Y

l. In apparatus for heating slabs and the like, the combination of aplurali-ty of Yfurnace units each having a pair of vertically displacedcharnbers in open .communication with each other,

each of said chambers having axially aligned entrance land exitopenings, means to mount said furnace units in axial alignment with eachother, means located between eac-h unit and on a rlevel with saidopenings for forwarding slabs through Yone set of chambers inone'di-rect-ion and through the .other set of chambers in theOpposite'direction, means in the lowercham-ber of each 'unit to heatslabs in said chambers, a transfer device having an elongated chambertherein to receive a slab, means to mount said transfer device formovement from a position in which its chamber is aligned with the upperset of said openings :to receive slabs therefrom to a position inl whichit is aligned with the lower set of said openingsto deliver slabsthereto, :and means to feed slabs into and out of the chamber of saidtransfer device.

2. In `apparatus for heating slabs and the like the combination of a rowcf individual and axially aligned furnace units, each furnace .unithaving a pair of vertically displaced and communicating chambers inwhich slabs .are heated, conveying means for slabs in each chamberlocated between the furnace units, drive means for said conveying meansoperative to move slabs in Y one direction throughV the upper chambersand chamber, said transfer device including means forming an elongatedchamber in which a slab may be received, mechanism operative to shiftsaid transfer device `from a position in which it is aligned with one ofthe rows of chambers of said furnace units to a position in which it isaligned with the other row of chambers of the.

furnace units, and means carried by said transfer device to move slabsinto and out of the chamber thereof.

3. The method of heating slabs and the like in a row of separate heatingunits each comprising Aa heating chamber and a preheating chamberlocated vertically above the heating chamber and in direct communicationtherewith which comprises the steps of moving the slabs one after theother in one direction through the preheating chambers, receiving theslabs from the preheating chambers, moving them downward to a positionaligned with said heating chambers, moving the slabs in the oppositedirection through said heating chambers, protecting the slabs fromsubstantial loss of heat from the time they leave v said 'preheatingchambers until they enter said f heating chambers, heating the slabs insaid heating chambers by radiant heat and hot products of combustion,and in said preheating chambers by hot products of combustion, andmoving said slabs in each direction from points between said heatingunits.

FREDERIC O. HESS.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,788,977 Blockinger Jan. 13,1931 1,946,971 Harter Feb. 13, 1934 2,214,157 rBannister Sept. 10, 19402,473,629 Andrews June 21, 1949 OTHER REFERENCES Pages 8 and 9 of TrinksIndustrial Furnaces, vol. I, third edition, copyright 1944. Published byJohn Wiley and Sons, New York, N. Y.

